Officials are probing how a 51-year-old highway bridge came to collapse in the Italian port city of Genoa yesterday, killing at least 26 people and injuring 16 others as it sent dozens of vehicles tumbling into a heap of concrete and twisted steel.

Ex-Digger thought killed in Afghanistan could be waging war in Syria

A former Australian soldier thought to have been killed in Afghanistan could be alive and fighting with al Qaeda's Syrian affiliate.

The revelation was made in the Long War Journal citing the latest edition of Al Risalah magazine, which is reportedly linked to Jabhat al-Nusra.

The jihadi magazine profiles a fighter using the nom de guerre "Usama Hamza Australia", who hails from Queensland and served in the ADF before joining al Qaeda 14 years ago.

The man's story appears to similar to that of Matthew Stewart, who also comes from Queensland and served as a soldier in East Timor before leaving the military in 2001.

After quitting the ADF Stewart is believed to have travelled to Iran before allegedly crossing into Afghanistan where he was recruited by the Taliban.

The Al Risalah profile says Australi was based in Waziristan, in the lawless border area between Pakistan and Afghanistan, and Afghanistan before he travelled to "aid Jabhat al-Nusra and help the Muslims in Syria".

There have been a number of sightings of Stewart and in 2007 it was reported that he may have been training with al Qaeda in Pakistan.